From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752794AbbAVPYl (ORCPT ); Thu, 22 Jan 2015 10:24:41 -0500 Received: from mail-qc0-f175.google.com ([209.85.216.175]:33925 "EHLO mail-qc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752436AbbAVPYf (ORCPT ); Thu, 22 Jan 2015 10:24:35 -0500 Date: Thu, 22 Jan 2015 10:24:31 -0500 From: Tejun Heo To: Steven Rostedt Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Al Viro , Ingo Molnar , Andrew Morton Subject: Re: [RFC][PATCH 0/5] tracing: Add new file system tracefs Message-ID: <20150122152431.GC4507@htj.dyndns.org> References: <20150121171953.823177070@goodmis.org> <20150121230007.GA10389@kroah.com> <20150121204725.71933044@grimm.local.home> <20150121220701.22231849@grimm.local.home> <20150122031819.GA16561@kroah.com> <20150121225109.6b27b555@grimm.local.home> <20150122123212.GB25645@htj.dyndns.org> <20150122093249.6f4041a8@gandalf.local.home> <20150122145547.GB4507@htj.dyndns.org> <20150122101530.2175cf2b@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150122101530.2175cf2b@gandalf.local.home> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 22, 2015 at 10:15:30AM -0500, Steven Rostedt wrote: > > kernfs provides two sets of file operations. One is seq_file based > > and the other is direct read/write. In both cases, bouncing data > > between userland and kernel is handled by kernfs. If you already have > > existing read write ops implemented doing custom buffer handling and > > direct userland memory access, it'll take some adaptation but for a > > lot of cases this would consolidate duplicate code paths. > > Does it also handle splice? That's a key part of the tracing code. It doesn't yet. We can add it as a part of kernfs_syscall_ops tho which exists to support these specialized bypass operations. kernfs doesn't do much with these. It just passes over the calls to the registered callbacks. Thanks. -- tejun